import matplotlib.pyplot as plt;
import numpy as np;
x=np.zeros(25)
k=0
for i in range(-1,2):
    for j in range(0,4):
        x[k]=(1+j*0.25)*(2**i)
        k=k+1
        x[k]=-(1+j*0.25)*(2**i)
        k=k+1
x[24]=0
y=np.zeros(25)
plt.figure()
plt.scatter(x,y,marker='|')
plt.plot(x,y,'k')
plt.savefig("normal.png")